The present invention relates to a lock nut in which a locking pin is disposed in an oblique bore in the nut for engagement of the inner end of the pin against a threaded portion on which the nut is to be mounted, the inner end of the locking pin having a shape which fits the thread of the threaded portion.
It has long been known in the art to lock nuts on threaded shafts by means of locking screws and it also known in the art to mount locking pins in nuts. One example of such an assembly is disclosed in U.S. Pat. No. 2,520,122 according to which a hole is drilled in the nut wall from the inside of the nut. For the purposes of the drilling, the axis of the drilling tool is to make a sufficiently large angle in relation to the plane of one end of the nut that the drilling tool can be inserted at an oblique angle in the nut. The pin inserted in the oblique blind bore will, as a result, incline at an oblique angle in relation to the geometric axis of the nut. This angle is determined by the size of the hole in the nut, that is to say the smaller the hole, the steeper the angle, and vice verse. A variation of this arrangement is described in U.S. Pat. No. 3,254,689.
U.S. Pat. No. 1,204,695 calls for the provision of the nuts with radial locking members which may consist of softer material than the bolt on which the nut is to be mounted, and probably softer than the nut material itself.
A common disadvantage inherent in all of these prior art lock nuts is that the locking pin does not provide effective locking which prevents bearing play or fixes the nut to allow a certain bearing play. A further disadvantage is that after repeated use of the nut, effective locking can no longer be obtained.
These prior art lock nuts satisfy at best the requirements for once-over use but deteriorate repidly in effectiveness and can at most be re-used a few times before they must be rejected because of the strict requirements which are now placed on lock nuts, dependng upon the facts that the inner ends of the locking pins are changed in shape and worn when the nut is tightened and that the locking pins cannot be reset correctly.